Internal drive in external enclosure problem (someone help)

I just put a 1TB SATA Western Digital Caviar Black into a USB 2.0 enclosure and it refuses to spin down when idle (it runs non-stop). I've even tried going into disk utility and ejecting it to no avail. In other words, I can mount and unmount it, but it won't spin down.

Anyone know if this is common with internal drives in enclosures or could the enclosure be the problem?

Thanks

I would suspect a bad enclosure or one that is not designed for the capacity of the drive you placed in there. Take a look at the specs for the enclosure and see if it says anything about max capacity.